The present invention generally relates to a storage system and a data recovery method, and in particular relates to backup and recovery technology of data.
Storage systems that store data of enterprise information systems have conventionally played the role of protecting data. From the needs of data protection and the like, in the field of storage systems, there have been proposed a replication function and a CDP (Continuous Data Protection) function of creating a replication of operation data without stopping the enterprise information system and instantaneously recovering operation data from such replication when a disaster or an operation error occurs.
The replication function is a function where the storage system, upon receiving a replication command from the host computer, copies data stored in a volume to be replicated at that time (hereinafter referred to as the “target volume”) to another volume, and thereby creates a replication of the target volume. As a result of periodically executing the replication function, it is possible to discretely acquire the replication of the target volume. The point that can be recovered with the replication function is the point in time when the storage system creates a replication of the target volume.
The CDP function is a function where, when used simultaneously with the replication function, recovery to numerous points from few replications is enabled (for instance, refer to the specification of US Patent Application No. 2005/0028022A1; “Patent Document 1”).
In actuality, with the CDP function, when a storage system receives write request is received from the host computer, it creates a journal from the various types of control information (write destination address of write data and data length of write data) contained in the write request and the write data, and stores this journal. Subsequently, upon recovery, the storage system sequentially overwrites the write data contained in the journal to the replication of the target volume (hereinafter referred to as the “base volume”) acquired with the replication function (hereinafter referred to as the “journal application”).
According to this kind of CDP function, by selecting the journal to be applied to the replication of the target operation data, it is possible to recover the contents of the target volume other than the time the replication of the target volume was acquired.
In order to recover data at a point in time when the software running on the host computer is in a resting state, a point referred to as a recovery point to become the reference for recovering data is created. Here, after the host computer enters the software in a resting state, it issues a recovery point creation request to the storage system notifying a certain point in time as the recovery point.
Incidentally, by creating a special journal, the storage system that received the recovery point creation request is able to differentiate the journals created before the issue of the recovery point creation request and the journals created after the issue of the recovery point creation request. When the storage system thereafter receives a recovery request to the recovery point from the host computer, it recovers data of the recovery point by sequentially applying journals, up to the recovery point from the oldest journal, to the base volume.